Thermal diffusivity of proton and spallation neutron irradiated - PowerPoint PPT Presentation

Tungsten R&D at ESS Thermal diffusivity of proton and spallation neutron irradiated tungsten Jemila Habainy 1,2 Yongjoong Lee 1 , Yong Dai 3 , Srinivasan Iyengar 1,2 European Spallation Source 1 , Lund University 2 , Paul Scherrer Institut 3 7 th High Power Targetry Workshop, East Lansing, Michigan, June 2018

ESS Tungsten Target 2.5 m diameter, rotating, helium-cooled,  7000 pure tungsten bricks, 8x3x1 cm 3 • • 5 MW, 2.0 GeV, 14 Hz pulsed proton beam  357 kJ/pulse deposited in target,  100  C/pulse, max. temp 450  C, max. stress 100 MPa • • Accumulated damage max. 2 dpa/year (5-year lifetime) • Potential issues: Degradation of thermal and mechanical properties, severe irradiation-induced embrittlement, fatigue, oxidation, dpa/year in Tungsten 36 sectors Image by ESS-Bilbao 2 Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

Unirr. tungsten – Fatigue studies • Ramp up and normal beam pulses will cause thermal fatigue • Fatigue and tensile tests were conducted at 25°, 280° and 480°C • Comparing fatigue limits of rolled, forged and HIPed tungsten, from 4 different suppliers – J. Habainy et al. Fatigue behaviour of rolled and forged tungsten at 25°, 280° and 480 °C, J. Nucl. Mater., vol. 465, pp. 438-447, 2015 – J. Habainy et al. Fatigue properties of tungsten from two different processing routes, J. Nucl. Mater., vol. 506, pp. 83-91, 2018 3 Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

Unirr. tungsten – Fatigue studies Rolled HIPed 25 °C 280 °C 480 °C 480 °C Ductile to brittle transition temperature is high, some specimens are still completely brittle at 500°C 4 Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

PSI: SINQ Target Irradiation Program – STIP V • STIP-V Irradiated between 2007-2008 • 560 MeV/ 1.3 mA proton beam • 2x hot-rolled W bars, size: 60x8x1mm • 5-28 dpa, 100°-800 °C 560 MeV/ 1.3 mA Proton beam 5

STIP-V irradiated tungsten Rod 3 Rod 5 Two low dose samples: 3.9 dpa, 158 appm He, T irr 115 ° C 5.8 dpa, 245 appm He, T irr 140 ° C with approx. 2% Rhenium Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

LFA at PSI 8 Jemila Habainy

LFA – Light Flash Apparatus Thermal diffusivity = 0.1388  d 2 t 1/2 Thermal conductivity = Thermal diffusivity  Specific heat  Density https://www.netzsch-thermal-analysis.com/en/landing- pages/principle-of-the-lfa-method/ 9 Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

Thermal diffusivity – unirradiated 10 Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

Effect of surface preparation 11 Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

Akiyoshi, M., Fusion Engineering and Design (2018), https://doi.org/10.1016/j.fusengdes.2018.03.008 12

Thermal diffusivity – irradiated 13 Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

Effect of rhenium content on thermal diffusivity of unirradiated tungsten Unirradiated T. Tanabe et al. / Materials Letters 57 (2003) 2950 – 2953 F. Hofmann et al. / Scientific Reports volume 5, Article number: 16042 (2015) 14 Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

Effect of rhenium content on thermal diffusivity of neutron irradiated tungsten W and W-Re alloys (up to 25 mass % Re) were irradiated in the Japan materials test reactor (JMTR) reactor at 330 K to thermal and fast neutron fluences of 1.03  10 20 and 3.37  10 19 (E> 1 MeV), respectively. 15 Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

Effect of rhenium content on thermal diffusivity of neutron irradiated tungsten Normalised thermal diffusivity of gold ion irradiated tungsten 1 Thermal diffusivity 0.96 0.92 0.88 1E+11 1E+12 1E+13 1E+14 Fluence [ions/cm 2 ] Heavy ion irradiated tungsten foil 16 Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

Thermal diffusivity of annealed irradiated tungsten Annealed at 1000  C, 1 h 17 Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

Simulating temperature in ESS tungsten using LFA results Simulation model Temperature [  C] in ESS tungsten immediately after a pulse Standard material data LFA material data (irr W) 18

Simulating stress in ESS tungsten using LFA results Standard material LFA material data LFA material data + data 20 % increase in stiffness Equivalent stress in ESS tungsten immediately after a pulse 83 MPa  117 MPa 19

1.4 dpa, tested at 450 ° C Unirr. tested at 450 ° C 20 m m 20

Summary Studies of thermal and mechanical properties of irradiated tungsten: Thermal diffusivity – decreased by 28-51% lower, depending on temperature. Annealing of 3.9 dpa W, at 1000 °C for 1 h, resulted in a slight recovery of thermal diffusivity. Fatigue – lowest runout at 135 MPa. Rolled tungsten has higher fatigue limit but shows more scatter. Hardness – increased by almost 75 % at 3.5 dpa Ductility – tungsten shows zero ductility at ESS relevant temp., already at 1.3 dpa Oxidation – even 5 ppm impurity in He will oxidize tungsten 21